The invention concerns a stabilized aqueous, acid gold bath containing a dicyanogold(I)-complex, a complex former, a reducing agent and customary additives, for the electroless deposition of gold onto gold and metals which are more electronegative than gold, as well as alloys of these metals.
Gold baths for the electroless deposition of gold are already known. They involve an alkaline or acid gold bath, containing predominantly an alkalidicyanoaurate(I), a complex former, a reducing agent, as well as additives for increasing the velocity of deposition and for improvement of the adhesiveness (U.S. Pat. Nos. 4,091,128, 3,300,328, 4,154,877, 3,032,436, German Offenlegungsschrifts DE-OS 2,052,787, DE-OS 2,518,559). All of these baths have, as a rule, an unsatisfactory stability, decomposing during deposition of metallic gold.
These baths have the further disadvantage that at a pH-value less than 3 a decomposition of the dicyanoaurate(I)-complex into difficult to dissolve gold(I)-cyanide and hydrocyanic acid occurs.
The mentioned gold baths are, moreover, suited only for the gilding of metals that are more electronegative than gold. An optimal electroless deposition of gold onto gold is, on the other hand, not possible by means of these baths.